<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <div :class="a">11</div>
        <div :class="arr">22</div>
        <div :class="['box2',a]">33</div>
        <div :class="{active:isActive}">44</div>
        <div :class="{active:1==1}">44</div>
        <div :class="['box2',a,{active:1==1}]">55</div>
    </div>
    <script src="./vue.js"></script>
    <script>
        const vm = new Vue({
            el: '#app',
            data:{
                a:'box',
                arr: ['box','box2'],
                isActive: false
            }
        })
        
    </script>
</body>
</html>